The following U.S. Patents are incorporated herein by reference:
U.S. Pat. No. 4,642,057 discloses a marine propeller mounting arrangement having a sleeve member for mounting on a propeller shaft, a propeller having an inner hub which fits over the sleeve member and a cushion member fitting between the sleeve member and the propeller inner hub. The sleeve member includes radially extending projections registering with channels in the hub to positively drive the propeller, even in the event of failure of the cushion member. The propeller has an outer hub surrounding the inner hub to define an exhaust gas passageway through the propeller.
U.S. Pat. No. 4,795,382 discloses a marine drive unit having a lower gear case forming a torpedo housing. A pair of coaxial propeller shafts is mounted in the housing and carries a pair of propellers thereon. The propeller shafts are driven by a pair of opposed driving gears suitably connected through a generally vertical main drive shaft to a marine engine and mounted on the horizontal drive axis. A pair of thrust bearings adapted to carry forward thrust loads are respectively disposed adjacent the facing portions of the opposed driving gears, with the pair being separated by a spacer tightly confined there between. The spacer is locked against rotation but is freely floatable in an axial direction, and transfers the forward thrust load from one bearing to the other, so that the load is ultimately transferred from the outer propeller shaft to the inner central shaft.
U.S. Pat. No. 4,832,636 discloses a marine drive unit having a lower torpedo housing. At least one propeller shaft is mounted in the housing for rotation about a drive axis. The propeller shaft is driven by a driving gear suitably connected to a marine engine and mounted on the drive axis. A first forward thrust bearing is disposed between the driving gear and the housing. In addition, a second forward thrust bearing is disposed adjacent the forward end of the propeller shaft. A pre-loading device, in the present example a washer-like Belleville spring of a desired capacity, is disposed to provide an adjustable biasing force on the second thrust bearing.
U.S. Pat. No. 6,478,543 discloses a torque transmitting device for use in conjunction with a marine propulsion system, which provides an adapter that is attached in torque transmitting relation with a propulsor shaft for rotation about a central axis of rotation. The first insert portion is attached in torque transmitting relation with the adapter and a second insert portion is attached in torque transmitting relation with a hub of the propulsor hub which can be a marine propeller or an impeller. A third insert portion is connected between the first and second insert portions and is resilient in order to allow the first and second insert portions to rotate relative to each other about the central axis of rotation. The adapter is shaped to prevent compression of the first, second, and third insert portions in a direction parallel to the central axis of rotation. The relative shapes of the various components and the resilience of the third insert portion, which can be a plurality of titanium rods, provides significant compliance of the device under low torque magnitudes, but at higher torque magnitudes it provides a significantly decreased compliance to facilitate torque transfer between a propulsor shaft and the propulsor hub.
U.S. Pat. No. 7,086,836 discloses a torque transfer mechanism for a marine propulsion system, which provides a connector mechanism, a first torque transfer mechanism, and a second torque transfer mechanism. A plurality of rods can provide the first torque transfer mechanism and a polymer component is shaped to provide the second torque transfer mechanism. All torque below a preselected magnitude is transferred through the first torque transfer mechanism and, for magnitudes of torque above the threshold, torque is transferred by both the first and second torque transfer mechanisms. The connector mechanism has an outer surface that is not used to transfer torque between it and an inner hub of a propulsor.